Employee Benefit Plans (Tables)
 12 Months Ended
Dec. 31, 2016
Employee Benefit Plans  
Assumptions made for the purpose of estimating fair value

 

 

 

 

 

 

 

 

 

    

2016

    

2015

    

2014

 

Expected term of options (years)

 

6

 

6

 

6

 

Risk free interest rate

 

1.27% - 1.69%

 

1.52% - 1.87%

 

1.77% - 1.94%

 

Volatility

 

103.87% - 104.88%

 

104.03% - 105.29%

 

107.17% - 113.92%

 

 

Schedule of Share-based Compensation, Stock Options, Activity

A summary of stock option activity for the year December 31, 2016 is as follows (in thousands except share amounts):

 

 

 

 

 

 

 

 

 

 

 

 

 

    

 

    

 

    

Weighted

    

 

 

 

 

 

 

 

Weighted

 

Average

 

 

 

 

 

 

 

 

Average

 

Remaining

 

Aggregate

 

 

 

 

 

Exercise

 

Contractual

 

Intrinsic

 

 

 

Shares

 

Price

 

Terms

 

Value

 

Options outstanding at December 31, 2015

 
11,700,786

 

$
3.29

 
8.3

 

 

 

 

Granted

 
3,702,500

 

 
1.72

 

 

 

 

 

 

Exercised

 
(274,000)

 

 
0.37

 

 

 

 

 

 

Forfeited

 
(347,482)

 

 
2.91

 

 

 

 

 

 

Expired

 
(21,750)

 

 
49.18

 

 

 

 

 

 

Options outstanding at December 31, 2016

 
14,760,054

 

$
2.90

 
7.9

 

$
878

 

Options exercisable at December 31, 2016

 
7,368,564

 

 
3.28

 
7.0

 

 
878

 

Options unvested at December 31, 2016

 
7,391,490

 

$
2.52

 
8.9

 

 

 —

 

 

Nonvested Restricted Stock Shares Activity

A summary of restricted stock activity for the year ended December 31, 2016 is as follows (in thousands except share amounts):

 

 

 

 

 

 

 

 

    

 

    

Aggregate

 

 

 

 

 

Intrinsic

 

 

 

Shares

 

Value

 

Unvested restricted stock at December 31, 2015

 
204,444

 

 

 

 

Vested

 
(191,111)

 

 

 

 

Unvested restricted stock at December 31, 2016

 
13,333

 

$
16